Identification and Expression Analysis of the Potato (Solanum tuberosum L.) stu-miR482 Family Under Exogenous 24-Epibrassinolide Treatments and Alkaline Salt Stress

Potato (Solanum tuberosum L.) is the world’s fourth-largest staple crop. Alkaline salt stress is a major abiotic stress factor that severely limits the growth, yield, and quality of potatoes; however, little is known about the molecular basis of potatoes’ response to alkaline salt stress or the stress-alleviation mechanism mediated by 24-epibrassinoside. In this study, we conducted a genome-wide identification of the potato miR482 family and analyzed its response patterns under alkaline salt stress and 24-epibrassinoside-mediated stress relief. We identified a total of 9 mature stu-miR482 sequences and 5 precursor sequences; all precursors form typical stable hairpin structures and exhibit high evolutionary conservation among Solanaceae plants. Promoter analysis revealed multiple cis-acting elements in the promoter region associated with light signaling, plant hormones, and stress signaling. A total of 64 potential target genes were predicted, encompassing transcription factors, disease resistance, and signal transduction-related genes, forming a complex regulatory network. Phenotypic analysis confirmed that EBR significantly alleviates the growth inhibition in potatoes induced by alkaline salt stress. qRT-PCR analysis indicated that stu-miR482a-5p is the primary stress-responsive member in leaves; stu-miR482d-3p/5p exhibited the strongest regulatory response to EBR in roots; in potato stolons, all members of the miR482 family were significantly upregulated under alkaline salt stress, with stu-miR482d-5p showing extremely significant upregulation across all treatment groups. In summary, this study represents the first systematic characterization of the potato miR482 family, revealing its tissue differential functions in alkaline salt stress and EBR-mediated stress relief.